Process for the preparation of amidino phenyl pyrrolidine beta-alanine urea analogs

ABSTRACT

The invention herein is directed to a process for producing a lactam of the formula   &lt;IMAGE&gt;   from a methionine analog of the formula   &lt;IMAGE&gt;   by treating the methionine analog with trimethylsulfonium halide or trimethylsulfoxonium halide in the presence of a base in a suitable aprotic solvent. The invention herein is further directed to the preparation of amidinophenyl pyrrolidinyl  beta -alanine urea analogs using such methionine and lactam compounds as intermediates, which  beta -alanine urea analogs are useful as antithrombotics.

BACKGROUND OF THE INVENTION

The invention herein is directed to the cyclization of a methionineanalog to a lactam using new reaction reagents and conditions. Theinvention herein is further directed to the enantioselective synthesisof ethyl3-[[[[1-[4-(aminoiminomethyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]propionateacetate and related β-alanine analogs. Such compounds are useful asantithrombotic agents.

More specifically the invention herein is directed to the conversion ofa methionine analog such as ##STR3## to a lactam such as ##STR4## usingreagent and reaction conditions which are beneficial in comparison topreviously disclosed methodology for achieving such a conversion.

Friedinger et al., J. Org. Chem., 47, (104-109), 1982 disclose generalmethods for the synthesis of lactam-constrained dipeptide analogs usingthree different paths from protected chiral α-amino acids to lactams.Included within this disclosure is a method for cyclizing methionineanalogs to lactams via an alkylative cyclization involving a two stepprocedure using highly volatile and toxic methyl iodide and highlyreactive sodium hydride as reagents.

It would be desirable to provide a process for conversion of amethionine analog to a lactam via conditions which do not employvolatile, toxic or highly reactive reagents and which produces a lactamhaving high enantiomeric purity.

SUMMARY OF THE INVENTION

The invention herein is directed to a process for producing a lactam ofthe formula ##STR5## wherein R is a protecting group such ast-butoxycarbonyl (BOC) or carbobenzyloxy (CBZ) and Z is H, --CN, --CONH₂or CO₂ alkyl, from a methionine analog of the formula ##STR6## bytreating the methionine analog with trimethylsulfonium halide ortrimethylsulfoxonium halide in the presence of an inorganic or aminergicbase, such as alkali metal hydroxides, alkoxides or carbonates or atertiary amine, diazabicycloundecane (DBU), or Hunig's base[diisopropylethylamine (DIEA)], in a suitable aprotic solvent.

The invention herein is further directed to the preparation ofamidinophenyl pyrrolidinyl β-alanine urea analogs using such methionineand lactam compounds as intermediates, which β-alanine urea analogs areuseful as antithrombotics.

DETAILED DESCRIPTION OF THE INVENTION

The invention herein is directed to a process for producing a lactam ofthe formula ##STR7## wherein R is a protecting group such ast-butoxycarbonyl (BOC) or carbobenzyloxy (CBZ) and Z is H, --CN, --CONH₂or CO₂ alkyl from a methionine analog of the formula ##STR8## bytreating the methionine analog with trimethylsulfonium halide ortrimethylsulfoxonium halide (such as trimethylsulfonium iodide ortrimethylsulfoxonium chloride) in the presence of an inorganic oraminergic base in a suitable aprotic solvent.

The invention herein is further directed to the preparation ofamidinophenyl pyrrolidinyl β-alanine urea analogs using such methionineand lactam compounds as intermediates, which β-alanine urea analogs areuseful as anti-thrombotics. Such process includes treating a methionineanalog of the formula ##STR9## (wherein Z is --CN or --CONH₂) withtrimethylsulfonium halide or trimethylsulfoxonium halide in the presenceof a base, preferably potassium carbonate, in an aprotic solvent,preferably DMSO, to afford a lactam of the formula ##STR10## dehydratingwhen Z is --CONH₂ and deprotecting the lactam, reacting the resultingproduct with a β-amino ester in the presence of CDI to produce a urea ofthe formula ##STR11## treating the urea with hydroxylamine to produce anamidoxime, hydrogenating the amidoxime; and isolating a compound of theformula ##STR12## wherein R₁ is hydrogen, alkyl, aryl, arylalkyl, aheterocyclyl radical containing 1 to 3 heteroatoms or aheterocyclylalkyl and R₆ is selected from alkyl, aryl, arylalkyl oracyloxymethyl.

The general synthetic scheme is outlined in Scheme 1. Starting fromcommercially available materials, a suitably protected methionine(R=BOC, CBZ) is condensed with a substituted or unsubstituted aniline inthe presence of a suitable amino acid coupling reagent (e.g. isobutylchloroformate, 2-chloro-1-methylpyridinium iodide,1,1'-carbonyldiimidazole (CDI) or1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) and atertiary amine base (e.g. N-methylmorpholine, N-methylpiperazine ortriethylamine) in a suitable aprotic solvent (e.g. dimethylformamide(DMF), tetrahydrofuran (THF) or CH₂ Cl₂) at a temperature ranging from-15° C. to 25° C. to give the methionine analog 1.

Methionine analog 1 is cyclized to lactam 2 via a novel set of reactionconditions. Treatment of compound 1 with trimethylsulfonium halide ortrimethylsulfoxonium halide in the presence of an inorganic or aminergicbase (e.g. alkali metal hydroxide, alkali metal alkoxides, alkali metalcarbonates or tertiary amines such as DBU or Hunig's base), preferablyin the presence of potassium carbonate in a suitable aprotic solvent(e.g. DMF, dimethylacetamide (DMA), DMSO or THF) at a temperatureranging from 35° C. to 90° C. affords lactam 2. Historically, thisconversion was accomplished by an alkylative cyclization in a two stepprocedure requiring highly volatile and toxic methyl iodide and highlyreactive sodium hydride respectively as the principle reagents [c.f.Freidinger, R. M. et al., J. Org. Chem., 47, 104-109 (1982); Kottirsch,G. et al., Bioorg. Med. Chem. Letters, 3, 1675-1680 (1993)]. Further,the extent of racemization in the later process was dependant upon theworkup conditions. In the present invention, neither strong alkylatorsnor strong bases are required and the product is produced having highenantiomeric purity.

The lactam 2 can be dehydrated when Z is --CONH₂ to the nitrile 3 usingstandard reagents (e.g. trifluoroacetic anhydride (TFAA),trichloroacetic anhydride or thionyl chloride) in the presence of anamine base (e.g. Et₃ N, pyridine, N-methylmorpholine orN,N-diisopropylethylamine) in an aprotic solvent (e.g. THF, EtOAc,pyridine or DME).

Aromatic analogs of methionine undergo cyclization as illustrated inTable 1. For example, the nitrile compound 1b, prepared by dehydrating1a (TFAA, Et₃ N), was cyclized to lactam 10. Also, thecarbomethoxyanilides 1d and 1e undergo cyclization without subsequenthydrolysis of the ester function. This is important to note since estercontaining intermediates cyclized under the Freidinger conditionsundergo hydrolysis of the ester.

                  TABLE 1                                                         ______________________________________                                         ##STR13##                                                                     ##STR14##                                                                    compound        compound, yield                                               ______________________________________                                        1a, Z = 4-CONH.sub.2                                                                          2a, 75%                                                       1b, Z = 4-CN    10, 88%                                                       1c, Z = 4-H     2c, 38%                                                       1d, Z = 3-CO.sub.2 Me                                                                         2d, 53%                                                       1e, Z = 4-CO.sub.2 Me                                                                         2e, 79%                                                       ______________________________________                                    

Deprotection of the protecting group R with HCl or trifluoroacetic acid(TFA) (R=BOC) or H₂, Pd/C (R=CBZ) affords aminolactam 4. For R=BOC,excess anhydrous HCl or concentrated HCl (2.0-5.0 equivalents) insolvent (e.g. EtOAc, MeO-t-Bu, 1,4-dioxane or THF) at 5 to 50° C. for0.5-23 hours affords product as the hydrochloride salt. Additionally thefree base could be isolated as a precipitate by adding 1 equivalent ofbase (e.g. 1N NaOH) to an aqueous solution of the hydrochloride salt.

Synthesis of the urea product 5 is accomplished by sequential additionof an appropriate β-amino ester and aminolactam 4 to a suitable phosgeneequivalent (e.g. triphosgene, diphosgene, phosgene,1,1'-carbonyldiimidazole) in a suitable solvent (e.g. CH₂ Cl₂, CHCl₃,ClCH₂ CH₂ Cl, DMF, DMA, pyridine, dioxane, THF, benzene, toluene).Reaction of 5 with hydroxylamine hydrochloride in the presence of asuitable base (e.g. Et₃ N, (i-Pr)₂ NEt, NaOAc, NaOEt, NaOH) in asuitable solvent (e.g. MeOH, EtOH, H₂ O, DMF, DMA) provides theamidoxime intermediate 6. This material is hydrogenolyzed in thepresence of a suitable catalyst (e.g. Pd/C, Pt/C, Pd(OH)₂) in a suitablesolvent (e.g. MeOH, EtOH, i-PrOH or HOAc) in the presence of an acidcounterion (e.g. HOAc, HCl, HBr, methanesulfonic acid (MsOH), succinicacid, citric acid, H₃ PO₄, malic acid) affording the target compound 7as the corresponding acid salt. ##STR15##

The preferred method of preparing a preferred antithrombotic agent,namely, ethyl3-[[[[1-[4-(aminoiminomethyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]propionateacetate is illustrated in Scheme 2 and Scheme 2a. Treatment ofcommercially available N-BOC-L-methionine and 4-aminobenzamide with2-chloro-1-methylpyridinium iodide (CMPI) and N-methylmorpholine (NMM)in DMF affords the methionine amide 1A.

In the novel cyclization step, heating a mixture of 1A,trimethylsulfonium iodide and powdered K₂ CO₃ (potassium carbonate) inDMSO at 70° C. gives the chiral lactam 2A.

Formation of the nitrile 10 is carried out by dehydrating the primaryamide with a standard reagent (trifluoroacetic anhydride/Et₃ N) in THF.Removal of the BOC protecting group with HCl/EtOAc affords the aminehydrochloride 11. Sequential addition of β-alanine ethyl esterhydrochloride and compound 11 to 1,1'-carbonyldiimidazole inDMF/pyridine (1:1) affords the unsymmetrical urea 12.

Treatment of 12 with hydroxylamine hydrochloride/triethylamine inethanol gives the benzamidoxime 13. Hydrogenolysis of 13 with 4%palladium on carbon in acetic acid gives the target compound 14 as theacetate salt.

In Scheme 2B another preferred method is illustrated, whereinintermediate 1A is dehydrated to intermediate 1B. Subsequent cyclizationof 1B to 10 is accomplished as described for the conversion of 1A to 2A.Intermediate 10 is then utilized further as demonstrated in Scheme 2 and2a. ##STR16##

As illustrated in Scheme 3, classical resolution of commerciallyavailable ethyl 3-aminobutanoate with (R)-mandelic acid affordsenantiomerically pure mandelate salt 15 after three recrystallizationsfrom EtOAc. Sequential treatment of a suspension of1,1'-carbonyldiimidazole with 11 then 15 affords the unsymmetrical urea16. Treatment of 16 with hydroxylamine hydrochloride/triethylamine givesthe benzamidoxime 17 which undergoes hydrogenolysis in HOAc to give thetarget compound 18. ##STR17##

The Arndt-Eistert homologation (Scheme 4) of N-BOC-D-phenylglycineaffords the chiral β-amino ester 19. Treatment of 19 with dry HClaffords the amine hydrochloride 20. Elaboration of 20 as outlined inScheme 2a affords the target compound 21. ##STR18##

The β-amino acids and esters can be purchased or prepared fromcommercially available starting materials using known methods asillustrated in Scheme 5. The racemic β-heteroaryl β-amino acids can beprepared from the appropriate aryl aldehyde, malonic acid, and ammoniumacetate (Method 1) [Johnson and Livak, J. Am. Chem. Soc., 229 (1936)].The racemic β-alkyl β-amino acids can be prepared from the correspondingalkene and chlorosulfonyl isocyanate (CSI) which goes through theβ-lactam as shown in Method 2 [W. A. Szabo, Aldrichimica Acta, 23(1977); R. Graf, Angew. Chem. Int. Ed., 172 (1968)]. The β-lactam can beopened to the ethyl ester by treatment with anhydrous HCl in ethanol. Analternative method to form racemic β-amino esters is shown in Method 3.Nucleophiles can be added to 4-benzoyloxy-2-azetidinone to afford avariety of 3-substituted β-amino esters after treatment with anhydrousHCl in ethanol [K. Prasad et al., Vol. 19, Heterocycles, 2099 (1982)].The racemic β-amino acids and esters can be resolved using classicalmethods described in the literature [E. Fischer, H. Scheibler, R. Groh,Ber., 2020 (1910); E. Fischer, H. Scheibler, Annalen, 337 (1911)].

Chiral β-amino acids and esters can also be prepared using manydifferent approaches including the following methods: 1) homologation ofsuitably protected α-amino acids using the Arndt-Eistert reaction asshown in Method 4 [Meier and Zeller, Angew. Chem. Int. Ed., 32-43(1975); M. Rodriguez et al., Tetrahedron Lett., 5153 (1990); W. J.Greenlee, J. Med. Chem. 434 (1985) and references therein], 2) throughthe addition of an amine to α,β-unsaturated esters bearing a chiralauxiliary as shown in Method 5 [J. d'Angelo, J. Maddaluno, J. Am. Chem.Soc., 8112-14, (1986)], 3) through an enantioselective hydrogenation ofa dehydroamino acid as shown in Method 6 [see: Asymmetric Synthesis, Vol5, (J. D. Morrison, Ed.) Academic Press, New York, 1985], and 4) throughthe addition of enantiomerically pure amines to α,β-unsaturated estersas shown in Method 7 [S. G. Davies, O. Ichihara, Tetrahedron: Asymmetry,183-186 (1991)]. ##STR19##

As used herein the term "lower alkyl" refers to a straight or branchedchain hydrocarbon radical having from 1 to about 6 carbon atoms.Examples of such "lower alkyl" radicals are methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, neo-pentyl,hexyl, isohexyl and the like.

As used herein the term "lower alkenyl" refers to unsaturated acyclichydrocarbon radicals containing at least one double bond and 2 to about6 carbon atoms. Examples of such groups include, ethenyl, propenyl,butenyl, isobutenyl, pentenyl, hexenyl and the like.

As used herein the term "lower alkynyl" refers to unsaturated acyclichydrocarbon radicals containing one or more triple bonds and 2 to about6 carbon atoms. Examples of such groups are ethynyl, propynyl, butynyl,pentynyl, hexynyl and the like.

The term aryl as used herein denotes carbocyclic aromatic ring systemscomposed of one or more aromatic rings. Preferred aryl groups are thoseconsisting of one, two or three benzene rings. The term embracesaromatic radicals such as phenyl, naphthyl and biphenyl.

The term acyloxymethyl embraces groups of the formula ##STR20## whereinR₇ is alkyl or aryl as defined above.

As used herein the phrase "heterocyclyl radical containing 1 to 3heteroatoms" refers to monocyclic or bicyclic radicals wherein 1 to 3carbon atoms have been replaced with a heteroatom selected from oxygen,nitrogen or sulfur. Such rings can be saturated or unsaturated andinclude heteroaromatics.

The following non-limiting examples describe and illustrate methods forcarrying out the process of the present invention, as well as otheraspects of the present invention, and the results achieved thereby infurther detail. Both an explanation of, and the actual procedures for,the various aspects of the present invention are described whereappropriate. These examples are intended to be merely illustrative ofthe present invention, and not limiting thereof in either scope orspirit. Those of skill in the art will readily understand that knownvariations of the conditions and processes described in these examplescan be used to perform the process of the present invention.

Unless otherwise indicated all starting materials and equipment employedwere commercially available.

EXAMPLE 1 Preparation ofN-[(4-aminocarbonyl)phenyl]-4-methylthio-2(S)-[[(1,1-dimethylethoxy)carbonyl]amino]butanamide(1A) ##STR21##

A. To a solution of L-BOC-methionine (100.0 g, 0.40 mol),4-aminobenzamide (57.3 g, 0.42 mol) and CMPI (102.6 g, 0.40 mol) in 250ml of DMF at 0° C., under nitrogen, was added NMM (88 mL, 0.8 mol) overtwo minutes. The reaction mixture was stirred and allowed to graduallywarm to room temperature while stirring for 4 hours. The reaction wasquenched by the addition of 0.1N HCl (750 mL) over about 10 minutes.After stirring for about 30 minutes, the white precipitate was filtered,washed with H₂ O and dried affording 123.3 g (84%) of product [m.p.193.5°-195° C. (dec.)].

[α]_(D) ²⁵ =-23.0° (MeOH, c=10.85 mg/ml) Anal. calc'd. for C₁₇ H₂₅ N₃ O₄S.0.33H₂ O: Calc'd.: C, 54.67; H, 6.93; N, 11.25; S, 8.59. Found: C,54.63; H, 7.02; N, 11.05; S, 8.63.

B. The following compounds were made in a like manner substituting otheranilines for 4-aminobenzamide:

N-phenyl-4-methylthio-2(S)-[[(1,1-dimethylethoxy)carbonyl]amino]butanamide (1c),

¹ H-NMR (300 MHz, CD₃ OD) δ1.44 (s, 9H), 1.90-2.05 (m, 2H), 2.08 (s,3H), 2.58 (m, 2H), 4.34 (m, 1H), 7.08 (t, J=8 Hz, 1H), 7.29 (t, J=8 Hz,2H), 7.57 (d, J=8 Hz, 2H).

N-[(3-methoxycarbonyl)phenyl]-4-methylthio-2(S)-[[(1,1-dimethylethoxy)carbonyl]amino]butanamide(1d),

¹ H-NMR (300 MHz, CDCl₃) δ1.43 (s, 9H), 2.00-2.25 (m, 2H), 2.08 (s, 3H),2.63 (m, 2H), 3.82 (s, 3H), 4.65 (m, 1H), 6.18 (d, J=7 Hz, 1H,exchangeable), 7.24 (t, J=8 Hz, 1H), 7.71 (m, 2H), 8.19 (s, 2H), 9.58(s, 1H, exchangeable).

N-[(4-methoxycarbonyl)phenyl]-4-methylthio-2(S)-[[(1,1-dimethylethoxy)carbonyl]amino]butanamide(1e),

¹ H-NMR (300 MHz, CDCl₃) δ1.42 (s, 9H), 2.00-2.25 (m, 2H), 2.10 (s, 3H),2.64 (m, 2H), 3.90 (s, 3H), 4.62 (m, 1H), 6.03 (d, J=7 Hz, 1H,exchangeable), 7.58 (d, J=8 Hz, 2H), 7.88 (d, J=8 Hz, 2H), 9.53 (s, 1H,exchangeable).

C. Preparation ofN-(4-cyanophenyl)-4-methylthio-2(S)-[[(1,1-dimethylethoxy)carbonyl]amino]butanamide(1b),

To an ice cooled, stirred suspension of compound 1a (10.00 g, 27.23mmol) and triethylamine (16.5 g, 0.163 mol) in 40 mL of THF was addedTFAA (7.88 g, 37.53 mmol) at a rate to keep the internal temperaturebetween 5°-10° C. The resulting solution was stirred at 0° C. for 20minutes then quenched at 0° C. by slowly adding 45 mL of 2N HCl. Afterthe subsequent addition of 40 mL of saturated NaCl, the mixture wasextracted with EtOAc, washed with saturated NaHCO₃, dried (MgSO₄),treated with decolorizing charcoal (ca. 1 g) and filtered through a bedof silica gel using EtOAc as eluent. Removal of the solvent underreduced pressure produced a golden yellow oil which was dried to 9.50 gof a gummy foam under high vacuum.

¹ H-NMR (300 MHz, CDCl₃) δ1.47 (s, 9H), 2.02 (m, 2H), 2.13 (s, 3H), 2.18(m, 1H), 2.63 (t, J=7 Hz, 2H), 4.44 (m, 1H), 5.34 (broad, 1H,exchangeable), 7.57 (d, J=8 Hz, 2H), 7.63 (d, J=8 Hz, 2H), 9.07 (s, 1H,exchangeable).

EXAMPLE 2 Preparation of 1-[(4-aminocarbonyl)phenyl]-3(S)-[[(1,1-dimethylethoxy)carbonyl]amino]pyrrolidin-2-one (2a) ##STR22##

A. To a solution of the product of example 1a (3.00 g, 8.16 mmol) inDMSO (6 mL) was added trimethylsulfonium iodide (5.00 g, 24.48 mmol) andpowdered K₂ CO₃ (1.69 g, 12.24 mmol). The reaction mixture was stirredat 80° C. under nitrogen for 3 hours, cooled to room temperature anddiluted with H₂ O (30 mL). The white precipitate was filtered, washedwith H₂ O and dried affording 1.94 g (75%) of product which was useddirectly in the preparation of the compound of Example 3. An analyticalsample was prepared by recrystallizing the product from 1 part hoti-PrOH and diluting with 3 parts H₂ O [m.p. 225°-226° C. (dec)].

[α]_(D) ²⁵ =-14.1° (MeOH, c=9.90 mg/mL) Anal. calc'd. for C₁₆ H₂₁ N₃O₄.1 H₂ O: Calcd.: C, 56.96; H, 6.87; N, 12.46. Found: C, 56.78; H,6.56; N, 12.36.

B. The following compounds were made in a like manner substituting otherproducts of Example 1 (1b-1e) for Compound 1a:

N-(4-cyanophenyl)-3(S)-[[(1,1-dimethylethoxy)carbonyl]amino]pyrrolidin-2-one(3),

¹ H-NMR (300 MHz, CDCl₃) δ1.47 (s, 9H), 2.08 (m, J=1H), 2.80 (m, 1H),3.82 (m, 2H), 4.38 (m, 1H), 5.20 (broad s, 1H, exchangeable), 7.68 (d,J=8 Hz, 2H), 7.82 (d, J=8 Hz, 2H).

N-phenyl-3(S)-[[(1,1-dimethylethoxy)carbonyl]amino]pyrrolidin-2-one(2c),

¹ H-NMR (300 MHz, CDCl₃) δ1.43 (s, 9H), 2.00 (m, 1H), 2.80 (m, 1H), 3.81(m, 2H), 4.36 (m, 1H), 5.23 (broad, 1H, exchangeable), 7.18 (t, J=8 Hz,1H), 7.39 (t, J=8 Hz, 2H), 7.64 (d, J=8 Hz, 2H).

N-[(3-methoxycarbonyl)phenyl]-3(S)-[[(1,1-dimethylethoxy)carbonyl]amino]pyrrolidin-2-one(2d),

¹ H-NMR (300 MHz, CDCl₃) δ1.47 (s, 9H), 2.04 (m, 1H), 2.80 (m, 1H), 3.85(m, 2H), 3.93 (s, 3H), 4.38 (m, 1H), 5.23 (broad, 1H, exchangeable),7.47 (t, J=8 Hz, 1H), 7.86 (m, 1H), 8.10 (m, 2H).

N-[(4-methoxycarbonyl)phenyl]-3(S)-[[(1,1-dimethylethoxy)carbonyl]amino]pyrrolidin-2-one(2e),

¹ H-NMR (300 MHz, CDCl₃) δ1.48 (s, 9H), 2.04 (m, 1H), 2.80 (m, 1H), 3.83(m, 2H), 3.92 (s, 3H), 4.38 (m, 1H), 5.20 (broad, 1H, exchangeable),7.75 (d, J=8 Hz, 2H), 8.06 (d, J=8 Hz, 2H).

EXAMPLE 3 Preparation of1-(4-cyanophenyl)-3(S)-[[(1,1-dimethylethoxy)carbonyl]amino]pyrrolidin-2-one##STR23##

To a suspension of the product of example 2a (2.0 g, 6.27 mmol) andtriethylamine (5.23 mL, 37.6 mmol) in THF (20 mL) at 0° C. was addedneat trifluoroacetic anhydride (3.87 g, 18.8 mmol) dropwise over 5minutes. The solution was stirred at 0° C. for an additional 1 hour,warmed to room temperature then quenched by adding 20 mL of water. Thereaction mixture was partially concentrated to approximately 1/2 thevolume of THF whereupon the product precipitated. The precipitate wasfiltered, washed with water and dried affording 1.60 g (85%) of product(m.p. 152°-153.5° C.).

[α]_(D) ²⁵ =-11.4° (MeOH, c=9.65 mg/mL) Anal. calc'd. for C₁₆ H₁₉ N₃ O.1H₂ O: Calc'd.: C, 60.17; H, 6.63; N, 13.16. Found: C, 59.75; H, 6.30; N,13.14.

EXAMPLE 4 Preparation of 1-(4-cyanophenyl)-3(S)-aminopyrrolidin-2-oneHydrochloride ##STR24##

HCl gas was bubbled through a solution of the product of example 3 (62.0g, 206 mmol) in EtOAc (750 mL) at ambient temperature for 15 minutes.After an additional 30 minutes, the precipitated product was filtered,washed with EtOAc and dried affording 46.7 g (96%) [m.p. 253°-254.5° C.(dec.), >99.9% e. e.]. Enantiomeric purity was determined by chiral HPLCanalysis using a Crownpak CR(-) column (15 cm×4.0 mm) and isocraticelution with 1% aqueous HClO₄ at 1.2 mL/min. The detector was set at 254nm.

[α]_(D) ²⁵ =-20.8° (MeOH, c=10.63 mg/mL) Anal. calc'd. for C₁₁ H₁₂ N₃OCl.1/4H₂ O: Calculated: C, 54.55; H, 5.20; N, 17.35. Found: C, 54.51;H, 4.98; N, 17.40.

EXAMPLE 5 Preparation of Ethyl3-[[[[1-(4-cyanophenyl)-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]propionate##STR25##

To a suspension of 1,1'-carbonyldiimidazole (572 mg, 3.55 mmol) inpyridine (2.5 mL) at 5° C. under nitrogen was added solid ethyl3-amino-propionate hydrochloride (545 mg, 3.55 mmol). The resultingsolution was stirred at 5° C. for 15 minutes, diluted with 2.5 mL of DMFand removed from the ice bath. The product of example 4 (700 mg, 2.96mmol) was added all at once and the reaction mixture was stirred at75°-80° C. for 2 hours. After cooling to room temperature, the resultingsolution was diluted with 15 mL of 1N HCl. The white precipitate wasfiltered, washed with H₂ O and dried. Trituration and filtration frommethyl t-butyl ether afforded 844 mg of product (m.p. 168.5°-169° C.).Extractive work up of the filtrate with EtOAc afforded an additional 110mg of product (94% overall).

[α]_(D) ²⁵ =+9.5° (MeOH, c=9.45 mg/mL) Anal. calc'd. for C₁₇ H₂₀ N₄ O₄ :Calculated: C, 59.29; H, 5.85; N, 16.27. Found: C, 58.94; H, 5.71; N,16.13.

EXAMPLE 6 Preparation of Ethyl3-[[[[1-[4-(amino(hydroxyimino)methyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]propionate ##STR26##

To a suspension of the product of example 5 (104 g, 304 mmol) andhydroxylamine hydrochloride (42 g, 607 mmol) in EtOH (900 mL) was addedtriethylamine (61 g, 607 mmol). The reaction mixture was heated to60°-65° C. and stirred for 2 hours. The reaction mixture wasconcentrated under reduced pressure and diluted with H₂ O. Theprecipitate was filtered, washed with H₂ O and dried affording 110 g(96%) of product (m.p. 188°-190° C.).

[α]_(D) ²⁵ =-2.8 (MeOH, c=10.53 mg/mL) Anal. calc'd. for C₁₆ H₁₉ N₃ O:C, 54.10; H, 6.14; N, 18.56. Found: C, 53.76; H, 6.14; N, 18.52.

EXAMPLE 7 Preparation of Ethyl3-[[[[1-[4-(aminoiminomethyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]propionateAcetate. ##STR27##

To a suspension of the product of example 6 (250 g, 663 mmol) in HOAc (1L) was added 100 g of 4% Pd/C (50% wet). The mixture was hydrogenated at60° C. using 60 psi H₂ for 1.37 hours. The catalyst was filtered and thesolvent evaporated under reduced pressure. The syrupy product wasdiluted sequentially while stirring with 500 mL MeOH, 1.5 L EtOH and 800mL of CH₃ CN. The white solid was filtered, washed with CH₃ CN and driedaffording 219 g of product. The mother liquor was concentrated and theresidue dissolved in H₂ O and treated with decolorizing charcoal (5 g).After filtration and removal of the solvent under reduced pressure, theresidue was dissolved in a minimal amount of HOAc and dilutedsequentially with 150 mL of i-PrOH and 150 mL of CH₃ CN. The precipitatewas filtered, washed with i-PrOH/CH₃ CN (1:1) and dried affording anadditional 35 g of product (91% overall) [m.p. 213°-214° C. (dec.)].Enantiomeric purity was determined by chiral HPLC using a Chiralcel-ODcolumn and EtOH/Heptane/TFA (20:80:0.1) as the mobile phase and wasdetermined to be >99.9% e. e..

[α]_(D) ²⁵ =+13.2 (MeOH, c=9.43 mg/mL) Anal. calc'd. for C₁₉ H₂₇ N₅ O₆ :C, 54.15; H, 6.461 N, 16.62. Found: C, 54.08; H, 6.57; N, 16.57.

EXAMPLE 8 Preparation of Ethyl 3(R)-aminobutanoate (R)-mandelate##STR28##

A solution of ethyl 3-aminobutyrate hydrochloride (4.5 g, 26.8 mmol) in27 mL of 1N NaOH was extracted 2× with EtOAc. The organic fraction wasdried (Na₂ SO₄) and concentrated under reduced pressure.Recrystallization of the residue 3× from EtOAc afforded 1.93 g (51%) ofproduct as a single chiral diastereomer as determined by NMRspectroscopy (m.p. 125°-125° C.). ¹ H-NMR (300 MHz, CDCl₃) δ1.00 (d, J=7Hz, 3H), 1.27 (t, J=7 Hz, 3H), 2.23-2.45 (m, 2H), 3.13 (m, 1H), 4.13 (q,J=7 Hz, 2H), 4.85 (s, 1H), 7.17-7.33 (m, 3H), 7.41 (d, J=8 Hz, 2H).

Anal. calc'd. for C₁₄ H₂₁ NO₅ : C, 59.35; H, 7.47; N, 4.94. Found: C,59.03, H, 7.51; N, 4.83.

EXAMPLE 9 Preparation of Ethyl 3(R)-[[[[1-(4-cyanophenyl)-2-oxo-3(S)-pyrrolidinyl]-amino]carbonyl]amino]butanoate ##STR29##

To a suspension of 1,1'-carbonyldiimidazole (178 mg, 1.1 mmol) inpyridine (2.5 mL) at 5° C. under nitrogen was added the product ofexample 4 (260 mg, 1.1 mmol). The resulting solution was stirred at 5°C. for 15 minutes, diluted with 2.5 mL of DMF and removed from the icebath. The product of example 8 (375 mg, 1.32 mmol) was added all at onceand the reaction mixture stirred at 75°-80° C. for 2 hours. Aftercooling to room temperature, the resulting solution was diluted EtOAcand washed with 1N HCl, saturated NaHCO₃ and dried (MgSO₄). Evaporationof the solvent afforded 295 mg (73%) of product (m.p. 177.5°-179° C.). ¹H-NMR (300 MHz, CDCl₃) δ1.20-1.30 (m, 6H), 2.05 (m, 1H), 2.53 (m, 2H),2.83 (m, 1H), 3.83 (m, 2H), 4.15 (q, J=7 Hz, 2H), 4.19 (m, 1H), 4.48 (m,1H), 7.68 (d, J=8 Hz, 2H), 7.82 (d, J=8 Hz, 2H).

Anal. calc'd. for C₁₈ H₂₂ N₄ O₄.0.1 H₂ O: Calculated: C, 60.02; H, 6.21;N, 15.56. Found: C, 60.29; H, 6.21; N, 15.06.

EXAMPLE 10 Preparation of Ethyl3(R)-[[[[1-[4-(amino(hydroxyimino)methyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]butanoate##STR30##

The title compound was prepared from the product of example 9 (250 mg,0.63 mmol) in a manner similar to example 6 affording 203 mg (83%) ofproduct [m.p. 165°-167° C. (dec.)]. ¹ H-NMR (300 MHz, d₆ -DMSO) δ1.06(d, J=7 Hz, 3H), 1.28 (t, J=7 Hz, 3H), 1.88 (m, 1H), 2.30-2.53 (m, 3H),3.75 (m, 2H), 3.95 (m, 1H), 4.05 (q, J=7 Hz, 2H), 4.40 (m, 1H), 7.56 (s,4H).

Anal. calc'd. for C₁₈ H₂₅ N₅ O₅.1/3H₂ O: Calculated: C, 54.40; H, 6.51;N, 17.64. Found: C, 54.76; H, 6.71; N, 17.21.

EXAMPLE 11 Preparation of Ethyl3(R)-[[[[1-[4-(aminoiminomethyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]butanoateAcetate ##STR31##

The title compound was prepared from the product of example 10 (150 mg,0.38 mmol) in a manner similar to example 7 affording 131 mg (77%) ofproduct [m.p. 209° C. (dec.)].

¹ H-NMR (300 MHz, d₆ -DMSO) δ1.08 (d, J=7 Hz, 3H), 1.19 (t, J=7 Hz, 3H),1.39 (s, 3H), 1.94 (m, 1H), 2.30-2.53 (m, 3H), 3.80 (m, 2H), 3.95 (m,1H), 4.06 (q, J=7 Hz, 2H), 4.43 (m, 1H), 7.86 (d, J=8 Hz, 2H), 7.91 (d,J=8 Hz, 2H).

Anal. calc'd. for C₂₀ H₂₉ N₅ O₆.3/4 H₂ O: Calculated: C, 53.50; H, 6.85;N, 15.60. Found: C, 53.34; H, 6.46; N, 15.35.

EXAMPLE 12 Preparation of Ethylβ(S)-[[(1,1-dimethylethoxy)carbonyl]amino]benzenepropanoate ##STR32##

To a stirred solution of N-BOC-D-phenylglycine (5.02 g, 20 mmol),N-methylmorpholine (2.02 g, 20 mmol) in EtOAc (100 mL) at 0° C. wasadded isobutyl chloroformate (2.73 g, 20 mmol). After 15 minutes thereaction mixture was filtered to remove the amine salts then an etherealsolution of diazomethane (60 mL, 30 mmol) was added. The cooling bathwas removed and the reaction mixture stirred at ambient temperature for2 hours. The reaction mixture was purged with nitrogen for 15 minutes toremove the excess diazomethane. The reaction mixture was diluted withEtOAc, washed with 1N HCl, saturated NaHCO₃, and dried (MgSO₄).Evaporation of the solvent afforded the crude diazoketone which wasdissolved in EtOH (100 mL) and then treated sequentially with AgO₂ CPh(1.6 g, 7 mmol) and triethylamine (6.06 g, 60 mmol). After 20 hours thereaction mixture was concentrated and chromatographed (silica gel, 15%EtOAc/hexanes) affording 4.90 g (85%) of product as a colorless oil. ¹H-NMR (300 MHz, CDCl₃) δ1.17 (t, J=7 Hz, 3H), 1.43 (s, 9H), 2.73-2.92(m, 2H), 4.07 (q, J=7 Hz, 2H), 5.10 (m, 1H), 5.48 (m, 1H), 7.22-7.39 (m,5H).

EXAMPLE 13 Preparation of Ethyl β(S)-aminobenzenepropanoateHydrochloride ##STR33##

Dry HCl gas was bubbled through a solution of the product of example 12(3.0 g, 10.2 mmol) in EtOAc (50 mL) at ambient temperature for 15minutes. After stirring for an additional 30 minutes, the solvent wasremoved under reduced pressure affording 2.30 g (98%) of product as ayellow oil. ¹ H-NMR (300 MHz, d₆ -DMSO) δ1.03 (t, J=7 Hz, 3H), 3.02 (dd,J=10 Hz, J=15 Hz, 1H), 3.25 (dd, J=6 Hz, J=15 Hz, 1H), 3.96 (m, 2H),4.55 (m, 1H), 7.3-7.6 (m, 5H), 8.93 (s, 3H).

EXAMPLE 14 Preparation of Ethylβ(S)-[[[[1-(4-cyanophenyl)-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]benzenepropanoate##STR34##

The title compound was prepared from the product of example 13 (685 mg,2.9 mmol) and the product of example 4 (600 mg, 2.9 mmol) in a mannersimilar to example 5 affording 1.09 g (91%) of product (m.p. 108°-109°C.). ¹ H-NMR (300 MHz, CDCl₃) δ1.16 (t, J=7 Hz, 3H), 2.00 (m, 1H),2.77-2.93 (m, 3H), 3.81 (m, 2H), 4.05 (q, J=7 Hz, 2H), 4.50 (m, 1H),5.26 (m, 1H), 7.20-7.35 (m, 5H), 7.66 (d, J=8 Hz, 2H), 7.80 (d, J=8 Hz,2H).

Anal. calc'd. for C₂₃ H₂₄ N₄ O₄.1/3H₂ O: Calculated: C, 64.79; H, 5.83;N, 13.14 Found: C, 64.65; H, 5.58; N, 13.18.

EXAMPLE 15 Preparation of Ethylβ(S)-[[[[1-[4-(amino(hydroxyimino)methyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]benzenepropanoate ##STR35##

The title compound was prepared from the product of example 14 (450 mg,1.07 mmol) in a manner similar to example 6 affording 431 mg (89%) ofproduct [m.p. 192° C. (dec.)]. ¹ H-NMR (300 MHz, d₆ -DMSO) δ1.10 (t, J=7Hz, 3H), 1.87 (m, 1H), 2.49 (m, 1H), 2.77 (m, 2H), 3.74 (m, 2H), 4.00(q, J=7 Hz, 2H), 4.41 (m, 1H), 5.10 (m, 1H), 7.20-7.40 (m, 5H), 7.69 (s,4H).

Anal. calc'd. for C₂₃ N₂₇ N₅ O₄.1/2H₂ O: Calculated: C, 59.73; H, 6.10;N, 15.14 Found: C, 59.67; H, 6.38; N, 14.85.

EXAMPLE 16 Preparation of Ethylβ(S)-[[[[1-[4-(aminoiminomethyl)phenyl]-2-oxo-3(S)-pyrrolidinyl]amino]carbonyl]amino]benzenepropanoateAcetate ##STR36##

The title compound was prepared from the product of example 15 (400 mg,0.88 mmol) in a manner similar to example 7 affording 335 mg (76%) ofproduct [m.p. 210°-211° C. (dec.)]. ¹ H-NMR (d₆ -DMSO) δ1.14 (t, J=7 Hz,3H), 1.93 (s, 3H), 2.03 (m, 1H), 2.47 (m, 1H), 2.80 (m, 2H), 3.84 (m,2H), 4.04 (m, 2H), 4.50 (m, 1H), 5.05 (t, J=7 Hz, 1H), 7.23-7.44 (m,5H), 7.92 (d, J=8 Hz, 2H), 7.97 (d, J=8 Hz, 2H).

Anal. calc'd. for C₂₅ H₃₁ N₅ O₆.1/2H₂ O: Calculated: C, 59.28; H, 6.37;N, 13.83 Found: C, 58.96; H, 6.21; N, 13.92.

What is claimed is:
 1. A compound of the formula ##STR37## wherein Z is selected from the group consisting of H, --CN, --CONH₂ or CO₂ alkyl; and R is selected from the group consisting of H, t-butoxycarbonyl and carbobenzyloxy.
 2. A compound of the formula ##STR38## wherein R₁ is selected from the group consisting of H, lower alkyl, and aryl; andwherein R₆ is selected from the group consisting of lower alkyl, aryl, arylalkyl and acyloxymethyl. 